For lack of a better idea, try the old voodoo of using Disk Utility to Repair Disk and Repair Permissions. If you don't feel like waiting to boot from the 10.6 DVD, you can run Verify Disk to see if anything comes up before you take the plunge. This may not help but it won't hurt.
Jon
macOS 11.7.10, iMac Retina 5K 27-inch, late 2014, 3.5 GHz Intel Core i5, 1 TB fusion drive, 16 GB RAM, Epson SureColor P600, Photoshop CC, Lightroom CC, MS Office 365
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